With development and progress of human society, due to improvement in life quality and promotion of society development, demand for energy source from people is increasing. However, the traditional fossil fuel is limited by gross output and its non-renewability while consumption of them leading to serious contamination product and greenhouse gas emissions. The sharp contradiction between current imminent depletion of fossil fuel and increasing demand for energy source from human and environmental protection occurs, seriously affecting the sustainable development of human society. Development and utilization of solar energy and other clean renewable energy is an important way to alleviate energy shortage, protect the natural environment and achieve sustainable development.
Solar energy is characterized to be unlimited reserve and clean energy, and thus is important to be exploited and developed for meeting increasing demand for energy source and reducing greenhouse gas discharge. However, due to low power density, instability and discontinuity of solar energy, it has a low annual generating efficiency of 10%-17% and high storage cost for individual usage of solar energy.
Solar energy thermochemistry technology is a type of solar energy thermal usage technology, by which collected solar energy is converted to chemical energy of fuel by an endothermic chemical reaction and the converted fuel can be stored and used for electricity generating with high efficiency, thereby achieving high efficient usage of solar energy and storage of solar thermal energy.
Nowadays study on solar energy thermochemical technology is focused on high temperature thermochemical technology, which is performed at a reactive temperature above 600° C. The technology mainly relates to water decomposition to generate hydrogen by solar energy and solar energy driven hydrogen generation with fossil fuel, etc. However, the high temperature thermochemical process is performed on the premise of using expensive solar energy collecting device while there are difficulties and bottlenecks of low heat-collecting efficiency, inconvenience of sun tracking and high requirement on material of reactors, etc, leading to less application of the technology.